Coronoid fracture patterns

Purpose: It has been suggested that specific types of coronoid fractures are associated strongly with specific patterns of traumatic elbow instability. This hypothesis was tested in a review of a large consecutive series of patients with a fracture of the coronoid as part of a fracture-dislocation of the elbow. Methods: One surgeon repaired 67 coronoid fractures as part of a fracture-dislocation of the elbow over a 7-year period. Each coronoid fracture was characterized on the basis of surgical exposure. Pearson chi-square analysis was used to evaluate the association of the coronoid fracture type with 1 of 4 common patterns of elbow fracture-dislocation. Results: The coronoid fracture was associated with an anterior (6 patients) or posterior (18 patients) olecranon fracture-dislocation in 24 patients, an elbow dislocation and radial head fracture in 32 patients, and a varus posteromedial rotational instability pattern injury in 11 patients. Among the 24 patients with olecranon fracture-dislocations 22 had large coronoid fractures and 2 had small (< 50%) coronoid fractures. All 32 patients with terrible-triad injuries had small (< 50%) coronoid fractures with 1 of these being a fracture of the anteromedial facet of the coronoid. Among patients with varus posteromedial rotational pattern injuries 9 had small fractures of the anteromedial facet and 2 had larger fractures. The association of coronoid fracture type with injury pattern was strongly statistically significant for both classification systems. Conclusions: The following strong associations were confirmed by this study: large fractures of the coronoid process with anterior and posterior olecranon fracture-dislocations, small transverse fractures with terrible-triad injuries, and anteromedial facet fractures with varus posteromedial rotational instability pattern injuries. An awareness of these associations and their exceptions may help guide the optimal management of these injuries.